Mysql Compare Two Tables

First, the importance of the index The index is used to quickly find a column in a particular value of the line. Instead of using an index, MySQL must start with the first record and then read the entire table until it finds the relevant row. The larger the table, the more time it takes. If the table in the query column index, MySQL can quickly reach a location to search the middle of the data file, there is no need to see all the data. Note that if you need to access most of the rows, sequential reads are much faster since we avoid disk searches. If you use Xinhua Dictionary to find "Zhang" the Chinese characters, do not use the directory, then ...

It is well known that query optimization is an unavoidable topic in any database. For database engineers, optimization is the most challenging job. MySQL Open source database is no exception. In fact, the author believes that the database optimization is not as much as we imagine the suffering. 　　Under normal circumstances, you can start from the following four details to do a good job in the MySQL database query optimization. First, use the Explain keyword to evaluate the flaw in the query statement as shown in the following figure, now the author in the database to execute a simple select ...

NoSQL has been in vogue for a long time, so what exactly is the scene you need to use these "emerging things", such as http://www.aliyun.com/zixun/aggregation/13461.html ">mongodb?" Here are some summaries: you expect a higher write load by default, compare transaction security, MongoDB more attention to high insertion speed. If you need to load a lot of low-value business data, then MONGO ...

With the explosion of information, micro-blogging website Twitter was born. It is no exaggeration to describe Twitter's growth with the word "born". Twitter has grown from 0 to 66,000 since May 2006, when the number of Twitter users rose to 1.5 in December 2007. Another year, December 2008, Twitter's number of users reached 5 million. [1] The success of Twitter is a prerequisite for the ability to provide services to tens of millions of users at the same time and to deliver services faster. [2,3,4 ...

Introduction: Pixable is becoming a light blog Tumblr (tumblr:150 The architectural challenges behind the amount of browsing), another hot social media, it is a photo-sharing center. But pixable can automatically grab your Facebook and Twitter images and add up to 20 million images a day, how do they handle, save, and analyze the data that is exploding? Pixable CTO Alberto Lopez Toledo and Engineering vice President Julio V ...

With the proliferation of data volume, Mysql+memcache has not met the needs of large-scale Internet applications, many organizations have chosen Redis as its architectural complement, however, redis the use of the threshold is not low, such as not supporting SQL, here for everyone to share the Redis use of the full raiders. Redis, one of the most closely watched NoSQL databases, has been used by many well-known internet companies, such as Sina Weibo, Pinterest and Viacom. However, being born with no support for SQL makes him look difficult ...

After more than eight years of practice, from Taobao's collection business to today to support all of Alipay's core business, and in the annual "Double Eleven Singles Day" continue to create a world record for the transaction database peak processing capacity.

MongoDB company formerly known as 10gen, founded in 2007, in 2013 received a sum of 231 million U.S. dollars in financing, the company's market value has been increased to 1 billion U.S. dollar level, this height is well-known open source company Red Hat (founded in 1993) 20 's struggle results. High-performance, easy to expand has been the foothold of the MongoDB, while the specification of documents and interfaces to make it more popular with users, this point from the analysis of the results of Db-engines's score is not difficult to see-just 1 years, MongoDB finished the 7th ...

The hardware environment usually uses a blade server based on Intel or AMD CPUs to build a cluster system. To reduce costs, outdated hardware that has been discontinued is used. Node has local memory and hard disk, connected through high-speed switches (usually Gigabit switches), if the cluster nodes are many, you can also use the hierarchical exchange. The nodes in the cluster are peer-to-peer (all resources can be reduced to the same configuration), but this is not necessary. Operating system Linux or windows system configuration HPCC cluster with two configurations: ...

PaaS (Platform-as-a-service) is a kind of cloud service, the service provider not only provides on-demand hardware and operating system services, but also provides the application platform and solution stack. For developers, PAAs greatly reduces the cost and pain of it deployments, providing resources for applications to scale more easily as needed. JVMs, application servers, and deployment packages (for example, war and ear) provide natural isolation for Java applications, allowing different developers to deploy applications in the same infrastructure, so JAV ...